The present invention relates generally to safety apparatus for a motor vehicle and in particular to a steering movement detector which detects the relative angular movement of the steering movements.
Vehicle safety apparatus are designed to alert vehicle occupant whenever a prolonged absence of steering operation is detected during normal driving condition. To detect the steering movements prior art devices have been designed to detect the angular displacement of a steering wheel from the neutral or absolute position and provides a clear signal indicating that the driver is active in steering operation whenever the displacement exceeds a predetermined fixed value. However, undesirable consequences might occur when a vehicle is driven along a roadway which is inclined sideways or when it encounters a strong transverse wind, because in such circumstances the driver will make an attempt to steer the vehicle to go straight by compensating for any departure from the intended path. In such circumstances steering movements can occur in the neighborhood of the set point of detection so that false clear signals will be produced by inconsequential steering movements.